get bitcoin transaction size with RPC command

get-bitcoin-transaction-size-with-RPC-command.md

command used:

• createrawtransaction
• fundrawtransaction
• signrawtransactionwithwallet
• decoderawtransaction

network: regtest

procedure:

> createrawtransaction "[]" "{\"bcrt1q4vchswyxqtz953q8ue24zdjxag38z50sl7d3xx\":0.01}"
> 02000000000140420f0000000000160014ab3178388602c45a4407e655513646ea227151f000000000

> fundrawtransaction "02000000000140420f0000000000160014ab3178388602c45a4407e655513646ea227151f000000000"
> {
  "hex": "02000000010e67533d77574802c9e24a97079081f2fb7f0c0d7bdce32a41717137458578e80000000000feffffff02bcabf39400000000160014763cf29805c86b0684bed8da0bea1acce1bb9dae40420f0000000000160014ab3178388602c45a4407e655513646ea227151f000000000",
  "fee": 0.00002820,
  "changepos": 0
}

> signrawtransactionwithwallet "02000000010e67533d77574802c9e24a97079081f2fb7f0c0d7bdce32a41717137458578e80000000000feffffff02bcabf39400000000160014763cf29805c86b0684bed8da0bea1acce1bb9dae40420f0000000000160014ab3178388602c45a4407e655513646ea227151f000000000"
> {
  "hex": "020000000001010e67533d77574802c9e24a97079081f2fb7f0c0d7bdce32a41717137458578e80000000000feffffff02bcabf39400000000160014763cf29805c86b0684bed8da0bea1acce1bb9dae40420f0000000000160014ab3178388602c45a4407e655513646ea227151f0024730440220454d3910112e9cb9ca0cb97f63a3ac29f19f4d692a9036f0bb8e21401184db4b02205c5c05e319ea9555746c8ebefc5219d2fbc4374a172e1e7aae4fdcad58fe87a9012102e5d0576239c65457f3c6f474409f835022dcbc2f55397af1441f714804e4db1b00000000",
  "complete": true
}

> decoderawtransaction 020000000001010e67533d77574802c9e24a97079081f2fb7f0c0d7bdce32a41717137458578e80000000000feffffff02bcabf39400000000160014763cf29805c86b0684bed8da0bea1acce1bb9dae40420f0000000000160014ab3178388602c45a4407e655513646ea227151f0024730440220454d3910112e9cb9ca0cb97f63a3ac29f19f4d692a9036f0bb8e21401184db4b02205c5c05e319ea9555746c8ebefc5219d2fbc4374a172e1e7aae4fdcad58fe87a9012102e5d0576239c65457f3c6f474409f835022dcbc2f55397af1441f714804e4db1b00000000
> {
  "txid": "d37ace6662da41dedd1c348d871497f64ffabd0658e6a1ebfbf057d94feeed68",
  "hash": "74b88b46e50892fc4f99c57fbf14c37dfb48fda911dee863a02360da4ee7f808",
  "version": 2,
  "size": 222,
  "vsize": 141,
  "weight": 561,
  "locktime": 0,
  "vin": [
    {
      "txid": "e8788545377171412ae3dc7b0d0c7ffbf2819007974ae2c9024857773d53670e",
      "vout": 0,
      "scriptSig": {
        "asm": "",
        "hex": ""
      },
      "txinwitness": [
        "30440220454d3910112e9cb9ca0cb97f63a3ac29f19f4d692a9036f0bb8e21401184db4b02205c5c05e319ea9555746c8ebefc5219d2fbc4374a172e1e7aae4fdcad58fe87a901",
        "02e5d0576239c65457f3c6f474409f835022dcbc2f55397af1441f714804e4db1b"
      ],
      "sequence": 4294967294
    }
  ],
  "vout": [
    {
      "value": 24.98997180,
      "n": 0,
      "scriptPubKey": {
        "asm": "0 763cf29805c86b0684bed8da0bea1acce1bb9dae",
        "hex": "0014763cf29805c86b0684bed8da0bea1acce1bb9dae",
        "reqSigs": 1,
        "type": "witness_v0_keyhash",
        "addresses": [
          "bcrt1qwc709xq9ep4sdp97mrdqh6s6ensmh8dwv9yhrv"
        ]
      }
    },
    {
      "value": 0.01000000,
      "n": 1,
      "scriptPubKey": {
        "asm": "0 ab3178388602c45a4407e655513646ea227151f0",
        "hex": "0014ab3178388602c45a4407e655513646ea227151f0",
        "reqSigs": 1,
        "type": "witness_v0_keyhash",
        "addresses": [
          "bcrt1q4vchswyxqtz953q8ue24zdjxag38z50sl7d3xx"
        ]
      }
    }
  ]
}

as showed in the result of last command:

  "size": 222,
  "vsize": 141,

reference: https://bitcoin.stackexchange.com/a/55352/81787 by Pieter Wuille

P.S. use command estimatesmartfee to get estimated transaction fees per KB.